1. Field of the Invention
The present invention relates to a dam storage library and, more particularly, to a data storage library which includes receptacle and picker modules that are alternately arranged in a checkerboard fashion.
2. Description of the Related Art
Data storage libraries have been implemented for archiving various types of recording media, such as magnetic tape, magnetic disks and optical disks. A tape or a disk may be fabricated in a container which may also be referred to as a "cartridge". Data storage libraries have a multiplicity of receptacles for storing these containers and include one or more pickers. Each picker transports a cartridge between a receptacle and a drive where the recording medium is read from or written to.
Most data storage libraries are not modular. One type of library includes a track and trolley combination which carries a picker for removing and replacing cartridges any place within the library. This generally requires two tracks, one along the full length of the library and one along the height of the library. Another type of library includes a carousel which is selectively rotated, and a picker which is selectively moved up and down with respect to the carousel. The carousel has a plurality of receptacles for receiving the media cartridges and the picker can be employed for removing and replacing the cartridges any place within the carousel. A fairly complex type of library employs a robotic arm which is selectively positioned anywhere within the library for removing and replacing cartridges.
One of the primary problems with prior art recordable media libraries is that they are fixed in size. When a customer wants a medium-size library, for example, the manufacturer may only have large or small sizes available. To meet the needs of the market, a manufacturer would have to have many sizes of libraries available, which complicates manufacturing and requires a large inventory. Consequently, there is a strong demand for a modular data storage library so that the exact size requirements of a customer can be met. With modularity library, the library can be custom-made, while the modules can be kept low in cost by mass production.
Another problem with prior art data storage libraries is that when a customer desires an expansion of an existing library, the practice is to replace it with a new one or undergo very expensive modifications. This is obviously very costly and results in a temporary shutdown of the customer's operation. Library modules should be compatible so that when a customer desires a larger library, an additional module or modules can be added to satisfy the increased size requirements.
Still another problem with prior art recordable media libraries is that when there is a malfunction of one of the operative components, the whole library is shut down and rendered useless. It would be desirable to keep a majority of the library operational when there is a failure of one or more components.
The inventors have filed two previous patent applications which cover modularized data storage libraries. One of the inventors, Chi Hung Dang, filed an application on Apr. 16, 1993, for "Recordable Media Cartridge Picker Assembly and Library", Ser. No. 08/260,614. Both inventors also filed an application on Nov. 3, 1993, for "Automated Data Storage Library Employing Picker with Multiple Action Directions", Ser. No. 08/147,228. In the first application, each module contained one or more columns of receptacles and a piker. When the modules are set side by side, the columns of receptacles are aligned along one axis while the pickers are aligned along another axis. In my second application, one type of module includes a single column of receptacles and another type of module includes a single picker. These modules can be placed adjacent one another in a repetitive fashion to configure the overall library as desired. The present invention draws upon some of the details of these prior art applications which are incorporated by reference herein.